Gowtham A. Rao, MD, PhD, MPH, from the University of South Carolina in Columbia, and colleagues conducted a retrospective cohort study to compare the risk of cardiovascular death and cardiac arrhythmia among U.S. veterans taking azithromycin or levofloxacin vs. amoxicillin. Participants included veterans (mean age, 56.8 years) who received an exclusive outpatient dispensation for amoxicillin (979,380 patients), azithromycin (594,792 patients), or levofloxacin (201,798 patients) between September 1999 and April 2012. Azithromycin was mainly dispensed for five days, while amoxicillin and levofloxacin were usually dispensed for 10 days or longer.

The researchers found that, compared with patients receiving amoxicillin, the risks of death and serious arrhythmia were significantly increased for patients receiving azithromycin (hazard ratios, 1.48 and 1.77, respectively) during Days 1–5, but the risks were not significantly different on treatment Days 6–10. An increased risk of death and serious cardiac arrhythmia was seen for patients receiving levofloxacin vs. amoxicillin for Days 1–5 (hazard ratios, 2.49 and 2.43, respectively). For both death and arrhythmia, the risks remained significantly elevated for Days 6–10 (hazard ratios, 1.95 and 1.75, respectively).

"There are usually multiple antibiotic choices available for older patients, especially those with cardiac comorbidities; physicians may consider prescribing medications other than azithromycin and levofloxacin," the authors write.